Bayonet force booster for add-on lens

ABSTRACT

An add-on lens assembly supporting an add-on lens for a camera includes a locking mechanism actuatable by the user in order to increase the attachment force between the lens and the camera. The add-on lens assembly may include a rotatable lock ring having a cam pin that navigates along a surface of a cam such that when the lock ring is rotated, the cam pin causes the cam to translate axially. Axial translation of the cam may compress a spring within the assembly and increase the attachment force between the lens assembly and the camera. The increased force between the add-on lens assembly and the camera may provide additional support for large or heavy assemblies.

TECHNICAL FIELD

This disclosure relates to systems and methods for attaching add-on lensassemblies to cameras or other imaging systems.

BACKGROUND

Thermal imaging cameras are used in a variety of situations. Forexample, thermal imaging cameras are often used during maintenanceinspections to thermally inspect equipment. Example equipment mayinclude rotating machinery, electrical panels, or rows of circuitbreakers, among other types of equipment. Thermal inspections can useinfrared (IR) energy detection to detect equipment hot spots such asoverheating machinery or electrical components, helping to ensure timelyrepair or replacement of the overheating equipment before a moresignificant problem develops.

Depending on the configuration of the camera, the thermal imaging cameramay also generate a visible light image of the same object. The cameramay display the infrared image and the visible light image in acoordinated manner, for example, to help an operator interpret thethermal image generated by the thermal imaging camera. Unlike visiblelight images which generally provide good contrast between differentobjects, it is often difficult to recognize and distinguish differentfeatures in a thermal image as compared to the real-world scene. Forthis reason, an operator may rely on a visible light image to helpinterpret and focus the thermal image.

In some embodiments, an add-on lens is used with the thermal imagingcamera to adjust the field of view acquired infrared or visible lightimages. Add-on lenses can be attached in a variety of ways, such as viaa bayonet mounting mechanism. When a bayonet mechanism is used to attachan add-on lens assembly that is used to change the focal length of alens system, alignment is very important, either to maintain performanceand/or boresight requirements. Typical bayonets used on an infraredcamera are limited in how large the lens can be. This is because thebayonet mechanism has a spring that provides an axial force to assurethe add-on lens is aligned with the base unit. If the spring force istoo high, it becomes difficult to attach the lens. Therefore, it is acompromise between how large a lens can be, and how difficult it is toattach a lens. Typical solutions for larger lenses are to provide anexternal support, which has to be carried separately and installed whenit is time to use the lens. This invention eliminates the need for thissupport, by increasing the axial force on the bayonet with a camoperated mechanism.

SUMMARY

Aspects of the disclosure are directed toward systems and methods forincreasing the support of an add-on lens assembly for a camera whilemaintaining ease of attachment for a user. Some embodiments of an add-onlens assembly include a lens housing and a lens mounted in the lenshousing defining an optical axis. The assembly can include a mountingmechanism coupled to the housing and configured to engage an attachmentassembly of a camera. The assembly can include a cam positioned adjacentto a portion of the lens housing including a cam slot, and a cam pinextending through the cam slot. The assembly can include a lock ringsupporting the cam pin and rotatable between a first lock ring positionand a second lock ring position. Rotating the lock ring from the firstlock ring position to the second lock ring position may cause the campin to navigate through the cam slot, forcing the cam to transition froma first cam position to a second cam position. Movement of the cambetween the first and second cam positions may effectively increase theforce between a portion of the assembly and the attachment assembly ofthe camera from a first force to a second force.

In some embodiments, the motion of the cam, and therefore in someexamples, the motion of the cam pin and lock ring, is resisted by one ormore springs. In some embodiments, the cam slot includes a first end anda second end wherein the cam pin navigates from the first end of the camslot to the second end as the lock ring is moved from the first lockring position to the second. At least one of the first and second endsof the cam slot may include a detent to provide a locking feel when thecam pin enters the detent.

The details of one or more examples are set forth in the accompanyingdrawings and the description below. Other features, objects, andadvantages will be apparent from the description and drawings, and fromthe claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective front view of an example thermal imaging camera.

FIG. 2 is a perspective back view of the example thermal imaging cameraof FIG. 1.

FIG. 3 is a functional block diagram illustrating example components ofthe thermal imaging camera of FIGS. 1 and 2.

FIG. 4 is a schematic representation showing engagement andcommunication between portions of the thermal imaging camera and anadd-on IR lens assembly.

FIG. 5 is a perspective view of an exemplary add-on lens assemblycoupled to an attachment assembly of the camera.

FIGS. 6A and 6B are side views of an add-on lens assembly illustratingexemplary adjustment of a lock ring from a first position to a secondposition.

FIGS. 7A-7C are side views of an add-on lens assembly illustrating anexemplary effect of adjusting a lock ring from a first position to asecond position when the lock ring is removed.

FIGS. 8A and 8B are exemplary diagrams illustrating the attachment of anadd-on lens assembly to an attachment assembly of a camera.

FIG. 9 is a cross-sectional view of an add-on lens assembly according tosome embodiments.

FIG. 10 is a process-flow diagram illustrating an exemplary method foroperating a camera with an add-on lens assembly.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description provides somepractical illustrations for implementing examples of the presentinvention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of ordinary skill inthe field of the invention. Those skilled in the art will recognize thatmany of the noted examples have a variety of suitable alternatives.

A thermal imaging camera may be used to detect heat patterns across ascene, including an object or objects, under observation. The thermalimaging camera may detect infrared radiation given off by the scene andconvert the infrared radiation into an infrared image indicative of theheat patterns. In some embodiments, the thermal imaging camera may alsocapture visible light from the scene and convert the visible light intoa visible light image. Depending on the configuration of the thermalimaging camera, the camera may include infrared optics to focus theinfrared radiation on an infrared sensor and visible light optics tofocus the visible light on a visible light sensor.

Various embodiments provide methods and systems for producing thermalimages with reduced noise using averaging techniques. To further improveimage quality and eliminate problems that may arise from averaging (e.g.blurring, ghosting, etc.), an image alignment process is performed onthe thermal images prior to averaging.

FIGS. 1 and 2 show front and back perspective views, respectively of anexample thermal imaging camera 100, which includes a housing 102, aninfrared lens assembly 104, a visible light lens assembly 106, a display108, a laser 110, and a trigger control 112. Housing 102 houses thevarious components of thermal imaging camera 100. The bottom portion ofthermal imaging camera 100 includes a carrying handle for holding andoperating the camera via one hand. Infrared lens assembly 104 receivesinfrared radiation from a scene and focuses the radiation on an infraredsensor for generating an infrared image of a scene. Visible light lensassembly 106 receives visible light from a scene and focuses the visiblelight on a visible light sensor for generating a visible light image ofthe same scene. Thermal imaging camera 100 captures the visible lightimage and/or the infrared image in response to depressing triggercontrol 112. In addition, thermal imaging camera 100 controls display108 to display the infrared image and the visible light image generatedby the camera, e.g., to help an operator thermally inspect a scene.Thermal imaging camera 100 may also include a focus mechanism coupled toinfrared lens assembly 104 that is configured to move at least one lensof the infrared lens assembly so as to adjust the focus of an infraredimage generated by the thermal imaging camera.

In operation, thermal imaging camera 100 detects heat patterns in ascene by receiving energy emitted in the infrared-wavelength spectrumfrom the scene and processing the infrared energy to generate a thermalimage. Thermal imaging camera 100 may also generate a visible lightimage of the same scene by receiving energy in the visiblelight-wavelength spectrum and processing the visible light energy togenerate a visible light image. As described in greater detail below,thermal imaging camera 100 may include an infrared camera module that isconfigured to capture an infrared image of the scene and a visible lightcamera module that is configured to capture a visible light image of thesame scene. The infrared camera module may receive infrared radiationprojected through infrared lens assembly 104 and generate therefrominfrared image data. The visible light camera module may receive lightprojected through visible light lens assembly 106 and generate therefromvisible light data.

In some examples, thermal imaging camera 100 collects or captures theinfrared energy and visible light energy substantially simultaneously(e.g., at the same time) so that the visible light image and theinfrared image generated by the camera are of the same scene atsubstantially the same time. In these examples, the infrared imagegenerated by thermal imaging camera 100 is indicative of localizedtemperatures within the scene at a particular period of time while thevisible light image generated by the camera is indicative of the samescene at the same period of time. In other examples, thermal imagingcamera may capture infrared energy and visible light energy from a sceneat different periods of time.

Visible light lens assembly 106 includes at least one lens that focusesvisible light energy on a visible light sensor for generating a visiblelight image. Visible light lens assembly 106 defines a visible lightoptical axis which passes through the center of curvature of the atleast one lens of the assembly. Visible light energy projects through afront of the lens and focuses on an opposite side of the lens. Visiblelight lens assembly 106 can include a single lens or a plurality oflenses (e.g., two, three, or more lenses) arranged in series. Inaddition, visible light lens assembly 106 can have a fixed focus or caninclude a focus adjustment mechanism for changing the focus of thevisible light optics. In examples in which visible light lens assembly106 includes a focus adjustment mechanism, the focus adjustmentmechanism may be a manual adjustment mechanism or an automaticadjustment mechanism.

Infrared lens assembly 104 also includes at least one lens that focusesinfrared energy on an infrared sensor for generating a thermal image.Infrared lens assembly 104 defines an infrared optical axis which passesthrough the center of curvature of lens of the assembly. Duringoperation, infrared energy is directed through the front of the lens andfocused on an opposite side of the lens. Infrared lens assembly 104 caninclude a single lens or a plurality of lenses (e.g., two, three, ormore lenses), which may be arranged in series.

As briefly described above, thermal imaging camera 100 includes a focusmechanism for adjusting the focus of an infrared image captured by thecamera. In the example shown in FIGS. 1 and 2, thermal imaging camera100 includes focus ring 114. Focus ring 114 is operatively coupled(e.g., mechanically and/or electrically coupled) to at least one lens ofinfrared lens assembly 104 and configured to move the at least one lensto various focus positions so as to focus the infrared image captured bythermal imaging camera 100. Focus ring 114 may be manually rotated aboutat least a portion of housing 102 so as to move the at least one lens towhich the focus ring is operatively coupled. In some examples, focusring 114 is also operatively coupled to display 108 such that rotationof focus ring 114 causes at least a portion of a visible light image andat least a portion of an infrared image concurrently displayed ondisplay 108 to move relative to one another. In different examples,thermal imaging camera 100 may include a manual focus adjustmentmechanism that is implemented in a configuration other than focus ring114, or may, in other embodiments, simply maintain a fixed focus.

In some examples, thermal imaging camera 100 may include anautomatically adjusting focus mechanism in addition to or in lieu of amanually adjusting focus mechanism. An automatically adjusting focusmechanism may be operatively coupled to at least one lens of infraredlens assembly 104 and configured to automatically move the at least onelens to various focus positions, e.g., in response to instructions fromthermal imaging camera 100. In one application of such an example,thermal imaging camera 100 may use laser 110 to electronically measure adistance between an object in a target scene and the camera, referred toas the distance-to-target. Thermal imaging camera 100 may then controlthe automatically adjusting focus mechanism to move the at least onelens of infrared lens assembly 104 to a focus position that correspondsto the distance-to-target data determined by thermal imaging camera 100.The focus position may correspond to the distance-to-target data in thatthe focus position may be configured to place the object in the targetscene at the determined distance in focus. In some examples, the focusposition set by the automatically adjusting focus mechanism may bemanually overridden by an operator, e.g., by rotating focus ring 114.

Data of the distance-to-target, as measured by the laser 110, can bestored and associated with the corresponding captured image. For imageswhich are captured using automatic focus, this data will be gathered aspart of the focusing process. In some embodiments, the thermal imagingcamera will also detect and save the distance-to-target data when animage is captured. This data may be obtained by the thermal imagingcamera when the image is captured by using the laser 110 or,alternatively, by detecting the lens position and correlating the lensposition to a known distance-to-target associated with that lensposition. The distance-to-target data may be used by the thermal imagingcamera 100 to direct the user to position the camera at the samedistance from the target, such as by directing a user to move closer orfurther from the target based on laser measurements taken as the userrepositions the camera, until the same distance-to-target is achieved asin an earlier image. The thermal imaging camera may furtherautomatically set the lenses to the same positions as used in theearlier image, or may direct the user to reposition the lenses until theoriginal lens settings are obtained.

During operation of thermal imaging camera 100, an operator may wish toview a thermal image of a scene and/or a visible light image of the samescene generated by the camera. For this reason, thermal imaging camera100 may include a display. In the examples of FIGS. 1 and 2, thermalimaging camera 100 includes display 108, which is located on the back ofhousing 102 opposite infrared lens assembly 104 and visible light lensassembly 106. Display 108 may be configured to display a visible lightimage, an infrared image, and/or a combined image that includes asimultaneous display of the visible light image and the infrared image.In different examples, display 108 may be remote (e.g., separate) frominfrared lens assembly 104 and visible light lens assembly 106 ofthermal imaging camera 100, or display 108 may be in a different spatialarrangement relative to infrared lens assembly 104 and/or visible lightlens assembly 106. Therefore, although display 108 is shown behindinfrared lens assembly 104 and visible light lens assembly 106 in FIG.2, other locations for display 108 are possible.

Thermal imaging camera 100 can include a variety of user input media forcontrolling the operation of the camera and adjusting different settingsof the camera. Example control functions may include adjusting the focusof the infrared and/or visible light optics, opening/closing a shutter,capturing an infrared and/or visible light image, or the like. In theexample of FIGS. 1 and 2, thermal imaging camera 100 includes adepressible trigger control 112 for capturing an infrared and visiblelight image, and buttons 116, which form part of the user interface, forcontrolling other aspects of the operation of the camera. A differentnumber or arrangement of user input media are possible, and it should beappreciated that the disclosure is not limited in this respect. Forexample, thermal imaging camera 100 may include a touch screen display108 which receives user input by depressing different portions of thescreen.

FIG. 3 is a functional block diagram illustrating components of anexample of thermal imaging camera 100. Thermal imaging camera 100includes an IR camera module 200, front end circuitry 202. The IR cameramodule 200 and front end circuitry 202 are sometimes referred to incombination as front end stage or front end components 204 of theinfrared camera 100. Thermal imaging camera 100 may also include avisible light camera module 206, a display 108, a user interface 208,and an output/control device 210.

Infrared camera module 200 may be configured to receive infrared energyemitted by a target scene and to focus the infrared energy on aninfrared sensor for generation of infrared energy data, e.g., that canbe displayed in the form of an infrared image on display 108 and/orstored in memory. Infrared camera module 200 can include any suitablecomponents for performing the functions attributed to the module herein.In the example of FIG. 3, infrared camera module 200 is illustrated asincluding infrared lens assembly 104 and infrared sensor 220. Asdescribed above with respect to FIGS. 1 and 2, infrared lens assembly104 includes at least one lens that takes infrared energy emitted by atarget scene and focuses the infrared energy on infrared sensor 220.Infrared sensor 220 responds to the focused infrared energy bygenerating an electrical signal that can be converted and displayed asan infrared image on display 108. A more detailed discussion ofcomponents of FIG. 3 may be found in U.S. Patent Application No.61/982,665, entitled “Methods for end-user parallax adjustment,” whichwas filed on Apr. 22, 2014, and is hereby incorporated by reference inits entirety.

The IR lens assembly 104 shown in FIG. 1 on the thermal imaging camera100 can comprise a base IR lens assembly that functions to collect IRenergy from an object scene and focus the IR energy on the focal planearray contained inside the camera. The thermal imaging camera 100 workswith the IR lens alone and can generate thermal images without using anyadd-on lens hardware. To achieve wider or narrower fields of view,however, the thermal imaging camera 100 is designed to work with a setof one or more add-on IR lenses (not shown in FIG. 1) that can beattached over the base IR lens assembly 104. In use, an operator canselect a desired add-on IR lens from a set of available add-on IR lensesand attach the selected add-on IR lens to the thermal imaging camera100. In some examples, an add-on lens is housed in an add-on lensassembly that is attachable to the camera 100. If desired, the selectedadd-on IR lens assembly can subsequently be detached from the thermalimaging camera 100 so the camera can either be used with the base IRlens assembly 104 alone or a different add-on IR lens assembly canattached to the camera. Different add-on IR lenses may be used, forexample, depending on the size of the object scene, the distance to thetarget under inspection, or the like.

In some embodiments, an add-on lens assembly may communicate with one ormore components of an add-on lens assembly. FIG. 4 is a schematicrepresentation showing engagement and communication between portions ofthe thermal imaging camera 100 and an add-on IR lens assembly 300, whenused. As shown, an add-on IR lens assembly 300 can comprise a localmemory storage 334 that stores data unique to the specific add-on IRlens assembly 300 being attached to the thermal imaging camera 100. Theadd-on IR lens assembly 300 can further include a sensor 332 fordetecting operating conditions such as a temperature sensor. In someembodiments, when the add-on IR lens assembly 300 is attached to thethermal imaging camera 100, the sensor 332 and/or local memory storage334 of the add-on IR lens assembly 300 are placed in communication withthe processor/FPGA 222 housed inside of the camera 100. Details ofcommunication between an add-on lens assembly such as add-on IR lensassembly 300 and a camera 100 are described in U.S. Patent ApplicationNo. 61/982,665, which is incorporated herein by reference.

As shown in FIG. 1, in some embodiments, the IR lens assembly 104 caninclude an attachment assembly 130 for receiving a mounting mechanism ofan add-on lens assembly. FIG. 5 is a perspective view of an exemplaryadd-on lens assembly coupled to an attachment assembly of the camera. Asshown, the add-on lens assembly 400 includes a lens 402 defining a lensplane and an optical axis 404 normal thereto. The add-on lens assembly400 further includes a mounting mechanism 406 for attaching to anattachment assembly 130 of a camera (such as camera 100). The lens 402can be secured to a housing 412 of the add-on lens assembly 400

Add-on lenses can be attached to the camera 100 by a variety of knownmethods, such as, for instance, a bayonet mount. In the case of abayonet mount, the attachment assembly may include openings forreceiving one or more tabs on the mounting mechanism of the lens. Theattachment assembly can include one or more grooves adjacent to theopenings into which the tabs of the mounting mechanism can be rotated,preventing the tabs from being removed from the attachment assembly. Inmany cases, the mounting mechanism and/or attachment assembly includesone or more springs configured to provide an axial force between the oneor more groove of the attachment assembly and the one or more tabs ofthe mounting mechanism. Such springs can act to secure the add-on lensin place against gravity or other external forces experienced by theadd-on lens assembly.

However, as described above, a bayonet mount may be limited by the sizeor weight of an add-on lens. For instance, a lens that is too heavy, orthat has a center of mass to far from the camera when attached, mayplace too large of a load on the attachment assembly, causing the one ormore springs to give. This may result in the add-on lens sagging withrespect to the camera, misaligning the add-on lens with the IR lensassembly 104. One solution to prevent such sagging can includeincreasing the spring constant associated with one or more springs onthe attachment assembly or the mounting mechanism. However, increasedspring tension may result in the add-on lens assembly 400 being moredifficult to align and attach to the IR lens assembly 104.

Accordingly, in some examples, the add-on lens assembly 400 can includea locking mechanism, such as a lock ring 408, configured to selectivelyincrease the attachment force between the add-on lens assembly 400 and acamera when actuated. The attachment force may be, for example, a springforce as described above with regard to the bayonet attachmentstructure. In the exemplary embodiment of FIG. 5, the lock ring 408 maybe rotated by a user to increase or decrease the attachment forcebetween the add-on lens assembly 400 and the camera, such as between theadd-on lens assembly 400 and attachment assembly 130. The add-on lensassembly 400 can include a pusher 414 proximate the mounting mechanism406 for engaging a portion of the attachment assembly 130 of the camera.For example, the adjusted attachment force may include a force betweenthe pusher 414 of the add-on lens assembly 400 and the attachmentassembly 130 of the camera. In some examples, the lock ring 408 isrotated about the optical axis 404 defined by the lens 402. Additionallyor alternatively, the lock ring 408 can be rotated about a portion ofthe housing 412 of the add-on lens assembly 400.

In some embodiments, the lock ring 408 may be rotatable between a firstposition and a second position. The lock ring 408 in the first positionmay correspond to a first attachment force between the add-on lensassembly 400 and the camera, while the second position may correspond toa second attachment force that is larger than the first attachmentforce. Accordingly, a user may attach the add-on lens assembly 400 tothe camera with the lock ring 408 in the first position, and thenactuate the lock ring 408 to the second position, increasing theattachment force.

In some examples, actuating the lock ring 408 between a first positionand a second position comprises moving the lock ring 408 relative to thehousing 412. For example, in the illustrated example, actuating the lockring 408 can include rotating the lock ring 408 relative to the housing412. In some embodiments, one or both of the lock ring 408 and thehousing 412 (or other fixed component relative to the movement of lockring 408) can include at least one indicator 418 for visually indicatingthe current position of the lock ring 408 to the user. As illustrated inthe exemplary embodiment of FIG. 5, the lock ring 408 includes anindicator 418 comprising an arrow that points toward a portion of thehousing 412. As the lock ring 408 rotates about the housing 412, theindicator 418 moves relative to the housing 412.

In the illustrated embodiment, the indicator 418 may move betweenportions of the housing 412 labeled “LOCK” and “UNLOCK.” In variousembodiments, these or other descriptors may be used to communicate tothe user information regarding the attachment force between the pusher414 and the attachment assembly 130. For instance, in the embodiment ofFIG. 5, the indicator 418 pointing toward “LOCK” indicates that theattachment force is higher than if the indicator 418 pointed toward the“UNLOCK” state. Accordingly, the user may know that, if the add-on lensassembly 400 is detached from a camera, it may be difficult to attachthe assembly 400 without adjusting the add-on lens assembly 400 to be inthe “UNLOCK” state.

FIGS. 6A and 6B are side views of an add-on lens assembly illustratingexemplary adjustment of a lock ring from a first position to a secondposition. In the illustrative embodiment of FIGS. 6A and 6B, the add-onlens assembly 400 includes a mounting mechanism 406 including at leastone tab 420, for example, for mounting to a bayonet mount of a camera.In the embodiment of FIG. 6A, the lock ring 408 is positioned in a firstlock ring position. In the first lock ring position, indicator 418points toward the “UNLOCK” marker on the housing 412. The add-on lensassembly 400 includes a pin 410 coupled to the lock ring 408, which maybe configured to move with the lock ring 408 as it is actuated.

In the embodiment of FIG. 6B, the lock ring 408 has been actuated fromthe first lock ring positon (e.g., as shown in FIG. 6A) to a second lockring position. In the second lock ring positon, indicator 418 pointstoward the “LOCK” marker on the housing 412. Thus, lock ring 408 hasbeen moved relative to the housing 412. As shown, pin 410 has moved withlock ring in moving between the first lock ring position and the secondlock ring position. It can be seen by a comparison of FIGS. 6A and 6Bthat in the illustrated embodiment, the lock ring 408 rotates relativeto the housing 412 and also the mounting mechanism 406. That is, intransitioning between the first and second lock ring positions, theindicator 418 and pin 410 move relative to the housing 412 and also thetab 420 of the mounting mechanism 406. Accordingly, when the mountingmechanism 406 is attached to an attachment assembly of a camera,actuating the lock ring 408 between first and second lock ring positionsdoes not affect the position of tab 420.

FIGS. 7A and 7B are side views of an add-on lens assembly illustratingan exemplary effect of adjusting a lock ring from a first position to asecond position when the lock ring is removed. In the embodiments,add-on lens assembly 400 includes a cam 430 positioned proximate to thehousing 412. The cam 430 includes a cam slot 432 having a first end 434and a second end 436, and a first length extending between the first end434 and the second end 436. In some embodiments, the first length of thecam slot 432 extends in a direction that is not parallel to the lensplane. Additionally or alternatively, in some examples, the first lengthof the cam slot 432 extends in a direction that is not normal to theaxis of rotation of the lock ring 408.

In the illustrated embodiment, the add-on lens assembly 400 include afirst spring 440 positioned between the cam 430 and a proximal portionof the housing 412. The first spring 440 can include one or more wavesprings that entirely or partially encircle a portion of the housing412. In other embodiments, spring 440 can include one or more linearsprings or an otherwise elastic material disposed around a portion ofthe circumference of the housing 412 proximate the cam 430. In someembodiments, the assembly 400 includes a second spring 442 positionedbetween the cam 430 and a distal portion of the housing 412. Secondspring 442 may have properties similar to the first spring 440, or maybe a different type of spring. In the illustrated embodiment of FIG. 7A,the cam 430 is in a first cam position, wherein the second spring 442 iscompressed and the first spring 440 is uncompressed.

As previously discussed, the add-on lens assembly 400 can include a pin410 coupled to the lock ring 408. In some embodiments, pin 410 comprisesa cam pin 410 having a first end coupled to the lock ring 408 and a freesecond end that extends through the cam slot 432 of the cam 430. In someembodiments, the housing 412 of the add-on lens assembly 400 includes aradial groove 416 located beneath the cam 430 for receiving the secondend of the cam pin 410. Cam slot 432 and radial groove 416 can be sizedso that cam pin 410 may navigate through the slot 432 or groove 416.

During operation, as the lock ring 408 rotates about a portion of thehousing 412, the cam pin 410 navigates through the first length of thecam slot 432. In some embodiments, the lock ring rotates about theoptical axis defined by the lens 402 of the add-on lens assembly 400,and does not substantially translate axially. For instance, in someembodiments, the lock ring 408 is held at a substantially fixed axialposition by one or more portions of the housing 412 preventing axialtranslation of the lock ring 408. Additionally or alternatively, the campin 410 extending into the radial groove 416 of the housing 412 mayprevent the lock ring 408 from translating axially.

In general, rotation of the lock ring 408 about a portion of the housing412 causes the cam pin 410 to move about the housing 412 in a directionthat is not parallel to the first length of the cam slot 432. Thisforces the cam 430 to translate axially as the lock ring 408 is rotated.In the illustrated embodiment of FIG. 7A, the cam pin 410 may move fromthe first end 434 of the cam slot 432, through the first length, to thesecond end 436 of the cam slot 432.

FIG. 7B is an exemplary diagram illustrating motion of the cam pin 410through cam slot 432. As shown in FIG. 7B, relative to FIG. 7A, the campin 410 has moved from the first end 434 to the second end 436 of thecam slot 432. As a result, cam 430 has translated axially and proximallyrelative to the housing 412 of the add-on lens assembly 400 (e.g., seeFIG. 7C). By moving proximally, the cam 430 has released at least someof the compression on the second spring 442, and has compressed firstspring 440.

FIG. 7C is a diagram illustrating the embodiments of FIGS. 7A and 7Baligned with one another. As shown by the dashes lines, the distal endof the housing 412, the tabs 420 on the mounting mechanism 406, the campin 410, and the radial groove 416 of the housing have not substantiallytranslated axially between the top and bottom diagrams. However, lines700, 702 illustrate that the cam 430 has translated axially andproximally relative to the rest of the add-on lens assembly 400.

As shown in the exemplary embodiments illustrated in FIGS. 7A-7C,actuating the lock ring 408 can cause the cam 430 to translate withinthe add-on lens assembly 400, changing the compression experienced infirst 440 and second 442 springs. FIGS. 8A and 8B illustrate the effectof such movement and compression when the add-on lens assembly isattached to the attachment assembly of a camera. FIGS. 8A and 8B areexemplary diagrams illustrating the attachment of an add-on lensassembly to an attachment assembly of a camera.

FIG. 8A illustrates a partially-rotated view of the embodiment of FIG.7A. In the illustrated embodiment, cam pin 410 extends through the firstend 434 of cam slot 432 in cam 430. The add-on lens assembly 400 isattached to the attachment assembly 130 of a camera by mountingmechanism 406. In the illustrated embodiment, the pusher 414 of themounting mechanism 406 is proximate the attachment assembly 130, butthere exists gap 460 therebetween. In some embodiments, gap 460 mayrepresent a spatial gap between the pusher 414 and the attachmentassembly 130. In alternative embodiments, gap 460 may be representativeof a first force between the pusher and the attachment assembly 130 ofthe camera.

In the illustrated embodiment of FIG. 8A, the cam 430 includes an axialslot 450 receiving an axial pin 452. Axial pin 452 may be secured to aportion of the housing 412 at a first end and extend outward into theaxial slot 450 at its second end. In some examples, the axial pin 452prevents cam 430 from substantially rotating, limiting its motion tosubstantially axial translation.

FIG. 8B illustrates a partially-rotated view of the embodiment of FIG.7B. In the illustrated embodiment, the cam pin 410 has navigated fromthe first end 434 to the second end 436 of cam slot 432 relative to theconfiguration of FIG. 8A. As described above with regard to FIGS. 7A-7C,such motion of the cam pin 410 causes cam 430 to translate proximallyand axially toward the mounting mechanism 406. Proximal cam 430 motioncompresses first spring 440 while relieving compression from secondspring 442. In the illustrated embodiment, compression of first spring440 forces pusher 414 of the mounting mechanism 406 against attachmentassembly 130 of a camera.

While shown between FIGS. 8A and 8B as eliminating gap 460, forcingpusher 414 against attachment assembly 130 may comprise increasing theforce between the components from a first force to a second force,greater than the first. The increased force between the pusher 414 ofthe mounting mechanism 406 and the attachment assembly 130 can act toincrease the supporting capability of the mounting structure. This mayallow for a longer, larger, or heavier add-on lens assembly 400 to besecured to the camera with reduced risk of the assembly sagging andreducing alignment between the add-on lens and the lens of the camera.In some exemplary embodiments, the second force is approximately fourtimes larger than the first force.

Increased force between the pusher 414 and the attachment assembly 130may make it difficult for a user to detach the add-on lens assembly 400from the camera. Accordingly, when operation using the add-on lens iscomplete, the user can move the lock ring 408 from the second lock ringposition back to the first lock ring position. In doing so, the cam pin410 navigates from the second end 436 of the cam slot 432 to the firstend 434, forcing the cam 430 to move distally. Distal motion of the cam430 releases pressure from the first spring 440, which can result in areduced force between the pusher 414 and the attachment assembly 130.Such a process can be represented by transitioning from theconfiguration of FIG. 8B to the configuration of FIG. 8A

In some embodiments, distal movement of the cam 430 may be resisted bycompression of the second spring 442. Resistance provided by the secondspring 442 may provide the user with a similar feeling in rotating thelock ring 408 in either direction. Further, in some examples, one orboth of first 434 and second 436 ends of the cam slot 432 can include adetent for receiving the cam pin 410 at the end of the cam slot 432.This can provide for a ‘locking’ feel for the user when the cam pin 410enters the detent(s), indicating that the lock ring 408 has fullytransitioned to one of the first or second lock ring positions.

FIG. 9 is a cross-sectional view of an add-on lens assembly according tosome embodiments. As shown, in the illustrated embodiment, add-on lensassembly 800 includes a lens 802 defining an optical axis 804. Lens 802is supported by housing 812, shown in a cross-hatch pattern for clarity.The add-on lens assembly 800 includes a mounting mechanism 806,including a tab 820 interfacing with a groove 132 of an attachmentassembly 130 of a camera. The assembly 400 includes a pusher 814proximate the attachment assembly 130. In the illustrative example ofFIG. 9, there exists a gap 860 between pusher 814 and attachmentassembly 130. As described above, the gap 860 may be a physical gap, ormay represent a first force between the pusher 814 and the attachmentassembly 130.

In the illustrated embodiment, the add-on lens assembly 800 includes alock ring 808 supporting a cam pin 810. The cam pin 810 extends inwardfrom the lock ring 808 into a radial groove 816 in the housing 812. Theadd-on lens assembly 800 includes a cam 830 disposed between the lockring 808 and a portion of the housing 812. As described with regard toprevious embodiments, cam 830 includes a cam slot 832 through which aportion of the cam pin 810 extends. The add-on lens assembly 400includes a first spring 840 disposed between the cam 830 and the pusher814, and a second spring 842 between the cam 830 and a portion of thehousing 812.

Similarly to the embodiments described above, in the embodiment of FIG.9, lock ring 808 may be rotated about the optical axis 804, causing campin 810 to navigate through the cam slot 832. In some examples,actuating the lock ring 808 from a first lock ring position to a secondlock ring position causes the cam pin 810 to move from a first end to asecond end of the cam slot 832. The cam pin 810 may move radiallythrough radial groove 816, and force the cam 830 to move proximallytoward the pusher 814.

As the cam 830 moves toward pusher 814, it compresses spring 840, whichin turn applies addition pressure to pusher 814. The additional pressureon pusher 814 can result in increased force between the pusher 814 andattachment assembly 130 of the camera. As previously described,increased force between the pusher 814 and the attachment assembly 130may increase the stability of the add-on lens assembly 800 mounted on acamera.

In the illustrated cross-section of the embodiment of FIG. 9, add-onlens assembly 800 includes a variety of counterpart components (labeled‘b’) of those described above. For example, assembly 800 includes lockring 808 b, radial groove 816 b, pusher 814 b proximate attachmentassembly 130 b, cam 830 b having cam slot 832 b, and a first spring 840b between the cam 830 b and the pusher 814 b. While not shown in FIG. 9,assembly can include a second cam pin having a first end fixed to lockring 808 b and a second end positioned to navigate through the secondcam slot 832 b and radial groove 816 b. Such components may operatetogether in the same way as described above. In some examples, anynumber of such components can be operatively connected to itscounterpart described previously. For example, cam 830 can at leastpartially encircle housing 812 so that the cam 830 and cam 830 b are asingle piece. The same can be true for any such components labeled ‘b’in FIG. 9, such as lock ring 808, spring 840, pusher 814, and the like.

In some examples, cam 830/830 b is a single piece at least partiallysurrounding housing 812, while cam slot 832 is not connected to cam slot832 b. In other examples, cam 830/830 b is a single piece at leastpartially surrounding housing 812 and cam slot 832/832 b combine todefine a single cam surface. In some such embodiments, lock ring 808/808b may be fully rotatable about the optical axis 804 while cam pin 810navigates along the cam surface. The cam surface may include a first setof segments, each segment in the first set of segments beingsubstantially parallel to the direction of the first length as describedwith regard to cam slot 832. The cam surface may include a second set ofsegments, each of the second set of segments disposed between segmentsin the first set of segments. Segments in the second set of segments mayextend in a direction substantially parallel to a second direction,different from the first. In some embodiments, the cam 830 can include adetent at one or more junctions between a segment in the first set ofsegment and a segment in the second set of segments.

In some such examples, as lock ring 808 is rotated about the housing812, cam pin 810 may move radially about the lens assembly 800 in afirst direction. When moving in the first direction, when the cam pin810 engages a segment in the first set of segments, it may force the cam830 to translate in a first axial direction (e.g., proximally). However,if the cam pin 810 moves in the first direction while engaging a segmentin the second set of segments, the cam 830 may move in a second axialdirection (e.g., distally). Similarly, if the lock ring 808 is rotatedin the opposite direction, cam pin 810 may move radially around thehousing 812 in a second direction, opposite the first. In suchoperation, when the cam pin 810 engages a segment in the first set ofsegments during lock ring 808 rotation, the cam 830 may translate in thesecond direction (e.g., distally). Similarly, when the cam pin 810engages a segment in the second set of segments during lock ring 808rotation, the cam 830 may translate in the first direction (e.g.,proximally). That is, in some such continuous-rotation examples,reversing the direction of rotation of the lock ring 808 may result ininterchanging which of the first and second sets of segments of the camsurface correspond to proximal and distal translation of the cam 830.Accordingly, in some such embodiments, the lock ring 808 may becontinuously rotated in a first direction about housing 812 torepeatedly increase and decrease the attachment force between themounting mechanism 806 and the attachment assembly 130. Similarly, thelock ring 808 may be continuously rotated in a second direction aboutthe housing 812 to repeatedly decrease and increase the attachmentforce.

Conversely, in some embodiments, counterpart (‘b’) components may bedisjoint from their corresponding components. That is, add-on lensassembly 800 can include separate cams 830 and 830 b, springs 840 and840 b, pushers 814 and 814 b, or any other such components. In stillfurther embodiments, add-on lens assembly 800 may exclude any suchcounterpart components, such as cam 830 b. For example, the assembly 800may include only a single cam 830 that does not surround housing 812. Ingeneral, in various embodiments, assembly 800 may include only singlecomponents such as cam 830, lock ring 808, pusher 814, spring 840, andthe like only surrounding a portion of the housing 812 without fullyencircling housing 812. It will be appreciated that various combinationsof single components, continuous components, or multiple separatecomponents may be used.

In various embodiments, the add-on lens assembly (e.g., 800) need notinclude all components illustrated. For example, as described,counterpart (‘b’) components of FIG. 9 may be excluded in someembodiments. Additionally or alternatively, embodiments may excludeother illustrated components, such as second spring (e.g., 842), or maycombine the functionality of components. For instance, in someembodiments, the functionality of the pusher (e.g., 814) and the firstspring (e.g., 840) may be combined into a single component. For example,the pusher (e.g., 814) may have spring-like properties and may itself becompressed by proximal motion of the cam (e.g., 830) and forced againstthe attachment assembly 130. Similarly, in some embodiments,functionality of the cam (e.g., 830) and the first spring (e.g., 840)may be combined into a single component. For instance, the cam mayinclude a spring-like portion such that, when the cam translatesproximally and presses against the pusher, the spring-like portion ofthe cam compresses. In still further embodiments, the functionalities ofthe cam (e.g., 830), the first spring (e.g., 842), and the pusher (e.g.,814) may be combined into a single component. For example, the cam mayinclude a cam slot (e.g., 832) for integrating with the cam pin (e.g.,810), a spring-like portion configured to compress under pressure, and apusher portion configured engage an attachment assembly of a camera. Insome such embodiments, when the cam pin (e.g., 810) navigates throughthe cam slot (e.g., 832), the cam moves proximally so that the pusherportion presses against attachment assembly of a camera. The pushingagainst the attachment assembly can cause the spring-like portion tocompress, maintaining a force between the pusher portion and theattachment assembly.

In still further embodiments, the functionality of the first spring(e.g., 840) can be omitted entirely. For instance, in some examples, andproximal motion of the cam (e.g., 830) may cause pusher (e.g., 814) tomove proximally toward an attachment assembly of a camera, causing it topress against the attachment assembly and increase the forcetherebetween. In further embodiments, the cam can include a pusherportion extending toward the proximal end of the add-on lens assembly.In some such embodiments, when the cam moves proximally, the pusherportion engages the attachment assembly of a camera, increasing theforce therebetween.

Embodiments of the add-on lens assembly (e.g., 400) can be utilized in amethod of operating a camera. FIG. 10 is a process-flow diagramillustrating an exemplary method for operating a camera with an add-onlens assembly. In the event that a user wishes to utilize an add-on lensin an imaging operation, the user can attach a mounting mechanism of anadd-on lens assembly housing the lens to an attachment assembly of thecamera (900). Attaching the mounting mechanism to the attachmentassembly can be performed in a variety of ways using a variety ofmechanisms, such as a screw-on or bayonet attachment scheme. Once theadd-on lens assembly has been attached to the camera, the user canactuate a locking mechanism of the add-on lens assembly (902). Actuatingthe locking mechanism can act to secure the add-on lens assembly to thecamera, reducing the risk of the lens sagging and causing opticalmisalignment between the add-on lens and the camera.

Once the add-on lens assembly is secured to the camera by actuating thelocking mechanism of the add-on lens assembly (902), the user can usethe camera with the add-on lens (904) until the use is complete (906).Once the use of the add-on lens is complete, the user can again actuatethe locking mechanism of the add-on lens assembly (908). Actuating thelocking mechanism from the locked position can unsecure the add-on lensassembly from the camera. Thus, after actuating locking mechanism, theuser can detach the mounting mechanism of the add-on lens assembly fromthe attachment assembly of the camera (910). Upon subsequent desired useof the add-on lens assembly, the user can repeat the process.

In some embodiments, actuating the locking mechanism of the add-on lensassembly (902) can comprise rotating a lock ring of the add-on lensassembly about an optical axis defined by the lens of the add-on lensassembly in a first direction (920). The rotation of the lock ring cancause a cam pin secured to the lock ring to navigate through a cam slotin a cam of the add-on lens assembly (922). Navigation of the cam pinthrough the cam slot can cause the cam to translate in a first axialdirection parallel to the optical axis (924). Translation of the cam cancompress a spring and increase the attachment force between the add-onlens assembly and the camera (926). This can secure the add-on lensassembly to the camera during use (904).

Once the use of the add-on lens assembly is complete (906), actuatingthe locking mechanism of the add-on lens assembly (908) can compriserotating the lock ring about the optical axis in a second direction(930). In some examples, the second direction can be opposite the first.In other examples, the second direction can be the same as the firstdirection in a continuously rotatable embodiment. Rotating the lock ringin the second direction can cause the cam pin to navigate through thecam slot (932), causing the cam to translate in a second axial directionparallel to the optical axis (934). In some embodiments, the secondaxial direction is opposite the first axial direction. Translation ofthe cam in the second axial direction (934) can release compression onthe spring to decrease the attachment force between the add-on lensassembly and the camera (936). Once the attachment force is decreased(936), the user may more easily detach the mounting mechanism of theadd-on lens assembly from the attachment assembly of the camera (910).

It will be appreciated that, while some described examples includeadd-on lens assemblies having infrared lenses for use with thermalimaging camera, structures and methods herein described may be used in avariety of optical configurations. For instance, add-on lens assembliessuch as those described may be used to attach an add-on visible lightlens to a standard visible light camera. In general, such structures canbe used to more securely attach an add-on lens to any appropriateoptical system without departing from the scope of the invention.Various lens assemblies have been described. These and others are withinthe scope of the following claims.

1. An add-on lens assembly for a camera comprising: a lens housing; amounting mechanism coupled to the lens housing and configured to engagean attachment assembly of the camera; a lens mounted in the lenshousing, the lens defining a central optical axis and a lens planenormal to the central optical axis; a cam positioned adjacent to aportion of the lens housing, the cam including a cam slot having a firstlength extending in a direction that is not parallel to the lens planeand being adjustable between at least a first cam position and a secondcam position; a pusher configured to abut or nearly abut at least aportion of the attachment assembly of the camera, wherein the forcebetween the pusher and the attachment assembly of the camera comprises afirst force when the cam is in the first cam position and a second forcewhen the cam is in the second cam position; a lock ring being rotatablebetween a first lock ring position and a second lock ring position; anda cam pin having a first end and a second end, the first end of the campin being fixed to the lock ring and the second end of the cam pinextending through the cam slot in the cam; whereby rotating the lockring from the first position to the second position causes the cam pinto navigate through the first length of the cam slot, forcing the cam totransition from the first cam position to the second cam position andchanging the force between the pusher and the attachment assembly of thecamera from the first force to the second force.
 2. The assembly ofclaim 1, wherein the first cam position and the second cam position aresuch that the cam transitioning from the first cam position to thesecond cam position comprises translating in a direction having acomponent parallel to the central optical axis.
 3. The assembly of claim2, wherein the first cam position is located distally relative to thesecond cam position, and wherein the second force is greater than thefirst force.
 4. The assembly of claim 1, further comprising a firstspring positioned between the cam and the pusher, wherein when the camtransitions from the first cam position to the second cam position, thecam compresses the first spring.
 5. The assembly of claim 4, furthercomprising a second spring positioned adjacent to and distal from thecam, the second spring being positioned between the cam and a portion ofthe housing, wherein the second spring provides resistance totransitioning the cam from the second cam position to the first camposition.
 6. The assembly of claim 5, wherein the cam slot has a firstend and a second end, the first length of the cam slot extending betweenthe first and second ends, and wherein each of the first and second endsof the cam slot comprises a detent for receiving the cam pin when thelock ring is in the first or the second lock ring positions,respectively.
 7. The assembly of claim 4, wherein the first spring, thecam, and the pusher are separate components.
 8. The assembly of claim 1,wherein the mounting mechanism comprises at least one tab configured tointerface with a groove of the attachment assembly in a bayonetconfiguration.
 9. The assembly of claim 1, wherein the lock ring has asubstantially circular cross-section and surrounds a portion of thehousing.
 10. The assembly of claim 9, further comprising a second campin having a first end coupled to the lock ring and a second end, andwherein the cam comprises a second cam slot for receiving the second endof the second cam pin.
 11. The assembly of claim 10, wherein the can hasa substantially circular cross-section and surrounds a portion of thehousing, the cam being positioned between the lock ring and the housing.12. The assembly of claim 10, further comprising a radial groovedisposed in the housing, the radial groove circumferentially surroundingthe housing and positioned to receive the second ends of the first andsecond cam pins.
 13. The assembly of claim 1, further comprising anindicator positioned on the lock ring for communicating the position ofthe lock ring to the user.
 14. The assembly of claim 1, furthercomprising an axial pin having a first end and a second end, the firstend secured to the housing; wherein the cam includes an axial slotextending in a substantially axial direction and receiving the secondend of the axial pin, such that motion of the cam is restricted totranslation in a substantially axial direction.
 15. The assembly ofclaim 1, wherein the lens is an infrared lens and the add-on lensassembly is configured for attachment to a thermal imaging camera.
 16. Amethod for using an add-on lens assembly with a camera, comprising:attaching a mounting mechanism of the add-on lens assembly to anattachment assembly of a camera, the attaching resulting in a firstattachment force between a surface of the mounting mechanism and asurface of the attachment assembly; and actuating a locking mechanism ofthe add-on lens assembly, the actuating of the locking mechanismeffectively increasing the attachment force between the surface of themounting mechanism and the surface of the attachment assembly from thefirst attachment force to a second attachment force greater than thefirst.
 17. The method of claim 16, wherein actuating a locking mechanismof the add-on lens assembly comprises rotating a lock ring in a firstdirection about an axis.
 18. The method of claim 17, wherein rotatingthe lock ring in the first direction about the axis causes a cam totranslate in a first axial direction substantially parallel to the axis.19. The method of claim 18, further comprising rotating the lock ring ina second direction about the axis, the second direction being oppositethe first, causing the cam to translate in a second axial direction,opposite the first axial direction, effectively decreasing theattachment force between the surface of the mounting mechanism and thesurface of the attachment assembly from the second attachment force tothe first force.
 20. The method of claim 18, wherein the axis comprisesan optical axis defined by a lens housed in the add-on lens assembly.